From Newsgroup: comp.lang.tcl

Hi, the following code is ugly:

proc block {args} {
set code [lindex $args end]
set args [lrange $args 0 end-1]
foreach {var val} $args {
uplevel [list push $var $val]
}
uplevel $code
foreach {var val} $args {
uplevel [list pop $var]
}
}

I want to have

macro block {args} {
local code var val
set code [lindex $args end]
set args [lrange $args 0 end-1]
foreach {var val} $args {
push $var $val
}
eval $code
foreach {var val} $args {
pop $var
}
}

the "macro" command evaluate the code IN the Frame of the calling "proc" arguments and "local" declared variables are local, all other variables
are always in the frame of the calling "proc"


mfg
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From Newsgroup: comp.lang.tcl


well the "args" in "prog" should be improved ...

proc block {args} {
set code [lindex $args end]
set args [lrange $args 0 end-1]
...
}

should be

proc block {args code} {
...
}

"args" always collect as much as possible arguments
{ args code } first set the defined "code" from the "end" and
all remaining arguments got to "args"

On 28.06.24 08:37, aotto1968 wrote:

Hi, the following code is ugly:

  proc block {args} {
    set code [lindex $args end]
    set args [lrange $args 0 end-1]
    foreach {var val} $args {
      uplevel [list push $var $val]
    }
    uplevel $code
    foreach {var val} $args {
      uplevel [list pop $var]
    }
  }

I want to have

  macro block {args} {
    local code var val
    set code [lindex $args end]
    set args [lrange $args 0 end-1]
    foreach {var val} $args {
      push $var $val
    }
    eval $code
    foreach {var val} $args {
      pop $var
    }
  }

the "macro" command evaluate the code IN the Frame of the calling "proc" arguments and "local" declared variables are local, all other variables
are always in the frame of the calling "proc"

mfg

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From Newsgroup: comp.lang.tcl

* aotto1968 <aotto1968@t-online.de>
| should be

| proc block {args code} {
| ...
| }

| "args" always collect as much as possible arguments
| { args code } first set the defined "code" from the "end" and
| all remaining arguments got to "args"

Note that the TCL 'args' works differently: it is only 'magic' if it is
the *last* entry in the argument list.

https://www.tcl.tk/man/tcl8.6/TclCmd/proc.htm
(*emphasis* added by me) :
There is one special case to permit procedures with variable numbers of
arguments. If the *last* formal argument has the name “args”, then a
call to the procedure may contain more actual arguments than the proce-
dure has formal arguments. In this case, all of the actual arguments
starting at the one that would be assigned to args are combined into a
list (as if the list command had been used); this combined value is as-
signed to the local variable args.

HTH
R'
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From Newsgroup: comp.lang.tcl

aotto1968 <aotto1968@t-online.de> wrote:

the "macro" command evaluate the code IN the Frame of the calling "proc" arguments and "local" declared variables are local, all other variables
are always in the frame of the calling "proc"

Tcl (standard Tcl) has no "macro" capability such as you would
typically find with a LISP.

You may be looking for the "sugar" package:

https://wiki.tcl-lang.org/page/Sugar

Which is a Tcl extension to add some amount of LISP like "macro"
capability to Tcl.

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From Newsgroup: comp.lang.tcl

Am 28.06.24 um 09:23 schrieb Ralf Fassel:

* aotto1968 <aotto1968@t-online.de>
| should be

| proc block {args code} {
| ...
| }

| "args" always collect as much as possible arguments
| { args code } first set the defined "code" from the "end" and
| all remaining arguments got to "args"

Note that the TCL 'args' works differently: it is only 'magic' if it is
the *last* entry in the argument list.

Yes, but it would indeed be useful; hence TIP 288 https://core.tcl-lang.org/tips/doc/trunk/tip/288.md

(unfortunately, rejected for 9.0)

Christian
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From Newsgroup: comp.lang.tcl

Sometimes tcl feels like the UDSSR "lada" car
→ everything is perfect and nothing have to be changed.

I already mentioned that tcl needs a "pragma" to activate a incompatible extension on a
per script basis

example:

pragma add args-everywhere

On 28.06.24 20:58, Christian Gollwitzer wrote:

Am 28.06.24 um 09:23 schrieb Ralf Fassel:

* aotto1968 <aotto1968@t-online.de>
| should be

|     proc block {args code} {
|       ...
|     }

| "args" always collect as much as possible arguments
| { args code } first set the defined "code" from the "end" and
| all remaining arguments got to "args"

Note that the TCL 'args' works differently: it is only 'magic' if it is
the *last* entry in the argument list.

Yes, but it would indeed be useful; hence TIP 288 https://core.tcl-lang.org/tips/doc/trunk/tip/288.md

(unfortunately, rejected for 9.0)

    Christian

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